A typical prior art hole cutter, or hole saw, includes a cylindrical blade body defining a plurality of saw teeth on the cutting edge of the blade body, and a plurality of apertures that are angularly spaced relative to each other about the blade body within an intermediate portion of the blade body. The apertures may define any of a variety of different configurations to facilitate inserting a tool into the apertures, such as a screw driver, to remove circular work piece slugs from within the interior of the blade body that result from cutting work pieces. The hole cutters are often coated, such as with paint, to protect the cutters against rust and/or for decorative or advertising purposes, such as with a particular manufacturer's distinctive color(s), trade dress, trademarks and/or logos.
One of the drawbacks encountered with some prior art hole cutters is that the coating is applied to all surfaces of the hole cutters, including all exterior and interior surfaces of the hole cutters, and therefore a relatively large amount of coating material is needed to coat the cutters. Since coating materials can be costly, these coating techniques can increase the manufacturing costs and, ultimately, increase the costs of the hole cutters to consumers.
Another drawback encountered with prior art hole cutters is that the interfaces of the blades bodies and work pieces, such at the cutting edges and the interior and exterior surfaces of the blade bodies adjacent to the cutting edges, can become heated due to the frictional forces between the rotating blade bodies and work pieces. The thermal energy created by such frictional forces gives rise to substantial heat that can soften or otherwise turn the coatings on these areas soft or gooey. Soft or gooey coatings act to increase frictional forces at the interfaces, and thereby reduce overall cutting speed and degrade the cutting efficiency of the hole cutters. A soft or gooey coating on the interior of a hole cutter can interfere with removal of a slug located therein, as a soft or gooey coating can stick to a slug and increase the frictional forces between the slug and the interior surface of the hole cutter to prevent the slug from being pushed or pried out of the interior of the cutter. Still further, the soft or gooey coatings can transfer from the hole cutters to work pieces, thereby staining, marking or otherwise tarnishing the work pieces.
Another drawback encountered with some prior art hole cutters is that they are unable to evacuate the volume of chips and/or dust created during cutting. The rate at which the chips and/or dust are generated during cutting can rapidly overcome the ability of some prior art hole cutters to allow for the egress of chips or dust away from the cutting edge, the interior of the bade body and/or other interfaces between the blade bodies and work pieces. The chips and dust that collect at the interfaces of the blade bodies and work pieces can become heated due to frictional forces created between the rotating blade body, collected dust and chips, and work piece. The thermal energy created by such frictional forces gives rise to substantial heat that can turn the coatings on the hole cutters soft or gooey. The soft or gooey coatings tend to trap dust and chips at the interfaces of the hole cutters and work pieces, such as at the cutting edge, and further degrade the cutting efficiency of the hole cutters.
Accordingly, it is an object of the present invention to overcome one or more of the above-described drawbacks and/or disadvantages of the prior art.